This application claims the benefit of Korean Application No. 97-77004, filed Dec. 29, 1997, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a copyright protection for a digital recording medium, and more particularly, to a copyright protection method and apparatus for a digital recording medium storing encrypted data and a copyright protected digital recording medium.
2. Description of the Related Art
In the future as well as at present, copyright protection for all contents or software used in audio/video (A/V) equipment or computer-related equipment is indispensable. Accordingly, hardware or software having various copyright protection functions is under development according to various standards or rules.
One of the currently developed or proposed copyright protection techniques utilizes the principle of a cryptosystem. There are a symmetrical cryptosystem represented by a data encryption standard (DES) and an asymmetrical cryptosystem represented by an RSA (Riverst, Shamir and Adleman), as a cryptosystem for encrypting information or a message itself. There are an authentication system and a content scramble system (CSS) as methods used to realize the above cryptosystems. There are a user authentication, a digital signature or a message authentication as the authentication system.
A macrovision, being a widely spread copyright protection technique, prevents a digital-to-analog copy. For example, when a copy or replica is attempted to be made into an analog magnetic tape as in a conventional video cassette recorder (VCR), the macrovision makes a sync signal continuously varied at random, to thus lower a picture quality abruptly. The content scramble system (CSS) being another copyright protection technique employs the authentication system and the cryptosystem at the same time, in order to prevent a digital-to-digital copy. The CSS is used for copyright protection of a digital versatile disk (DVD) ROM drive and a DVD decrypter card mounted on a computer. After the DVD-ROM drive and the DVD decrypter card have authenticated each other, encrypted A/V data which is recorded on a DVD-ROM is decoded through the decrypter card. That is, the DVD-ROM drive uses an incorporated chip or program to perform an authentication work with respect to the DVD decrypter card, and the DVD decrypter card uses an incorporated chip or program to perform an authentication work and a data decoding operation.
Meanwhile, a DVD player includes a separate chip or a micro-controller program which can decrypt encrypted data, and reads and reproduces the encrypted A/V data from a DVD without having an authentication procedure.
Using the above-described copyright protection techniques can only prevent unauthorized copies made by general users, but cannot prevent unauthorized copies made by technical copying experts.
To solve the above problems, it is an object of the present invention to provide a copyright protection method for a digital recording medium storing encrypted data.
It is another object of the present invention to provide a digital recording medium whose copyright is protected.
It is still another object of the present invention to provide an apparatus using a digital recording medium whose copyright is protected.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To accomplish the above and other objects of the present invention, there is provided a copyright protection method for protecting a copyright with respect to a digital recording medium, the copyright protection method including the steps of: (a) encrypting information to be recorded using a cryptosystem; (b) recording the information encrypted in step (a) on the digital recording medium; and (c) recording a cypher key necessary for decryption of the information encrypted in step (a) on the digital recording medium in a manner that the cypher key is not allowed to be copied.
There is also provided a digital recording medium including a data recording region on at least one part of which information encrypted using a cryptosystem is recorded; and a copy disapproval region on which a cypher key necessary for decryption of the encrypted information recorded on the data recording region is recorded.
There is further provided a playback apparatus for a digital recording medium including a data recording region on at least one part of which information encrypted using a cryptosystem is recorded; and a copy disapproval region on which a cypher key necessary for decryption of the encrypted information recorded on the data recording region is recorded, the playback apparatus including a memory for storing the cryptosystem; a reader for reading data recorded on the digital recording medium; and a decrypter for decrypting the encrypted information recorded on the digital recording medium, based on the cypher key read from the digital recording medium by the reader.
There is still further provided a digital recording and/or reproducing apparatus including a digital recording medium including a data recording region on at least one part of which information encrypted using a cryptosystem is recorded and a copy disapproval region on which a cypher key necessary for decryption of the encrypted information recorded on the data recording region is recorded; a memory for storing the cryptosystem; a reader for reading data recorded on the digital recording medium; and a decrypter for decrypting the encrypted information recorded on the digital recording medium, based on the cypher key read from the digital recording medium by the reader.